About 28 Days: The Daily Hormone Horoscope

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My Hormonology

What Your Cycle Reveals About Your Moods, Health and Potential—Updated and Expanded

Winner of the 2019 National Indie Excellence Award! 28 Days is back with an all-new updated and expanded edition! Each daily Hormone Horoscope® shows you what to expect from your mood, energy, love life, shopping habits and much more every day of your menstrual cycle. It will immediately change the way you plan your day, week and month ahead.

Written by Hormonology founder and women’s health journalist Gabrielle Lichterman, 28 Days is the book that launched the growing cycle-syncing movement among women worldwide.

Based on thousands of scientific studies, this book is the definitive guide to understanding how the hormones in your cycle impact you in virtually every way.

If you enjoy Gabrielle’s popular Hormone Horoscope Apps, you’ll love the depth of information she gives you about your hormones in her new edition of 28 Days. Plus, the book is full of study-backed tips that help make every day of your cycle better!

What you’ll learn in 28 Days:

  • Which days of your cycle your mood will be up or down
  • When your energy will be high or low
  • When you’ll be in the mood for romance, socializing and traveling
  • Which cycle days you’re less sensitive to pain
  • Study-backed ways to counter common cycle-related issues, such as fatigue,
    fogginess, menstrual cramps, blue moods, anxiety and stress
  • How to sync all your life’s daily activities—such as work, school, appointments,
    auditions, hobbies, trips and more—with your cycle
  • And much more!


  • Anyone with regular, healthy menstrual cycles. Your menstrual cycle can be the average 28 days, it can be shorter or longer than 28 days, or it can vary in length from cycle to cycle.
  • Anyone with a natural cycle. This means those who do not use hormone birth control (the Pill, patch, ring, implant, etc.) or supplemental estrogen, progesterone or testosterone for other reasons. That’s because these types of hormone medications alter the up and down pattern found in a typical natural menstrual cycle.
  • Adults ages 18 and over. This version of 28 Days includes frank sexual discussion intended for adults. 28 Days for Teens (available soon) is for those ages 12 to 17 with menstrual cycles and includes age-appropriate topics and language.

Because this book tracks the monthly ups and downs of estrogen, testosterone and progesterone in a natural, healthy menstrual cycle, it not intended for those who do not have a monthly menstrual cycle, are pregnant, breastfeeding, menopausal, taking hormone medications or hormone birth control, have a health condition that impacts reproductive hormones, such as polycystic ovarian syndrome, or do not have functioning ovaries.

Have functioning ovaries, but no uterus? If you ovulate, you can still use 28 Days to track your hormones.

This book is not intended in any way to help readers avoid pregnancy or become pregnant.